http://www.adammillerrealtor.com/dslr-camera-lenses-explained/
help with DSLR CAMERA LENSES?
I am teaching myself photography and I have a good grasp of composition, lighting and editing photos and just recently I have been trying to get to grips with the aperture and shutter speeds and ISO. But one thing I am really struggling with are the different lenses??
If anyone has the time to simply explain what the numbers relate to and what should be used for what I would be very gratefull. Alternatively if anyone knows a good book that would explain? Thanks.
Have you read your camera’s manual? They often have some useful information in them on how to operate your camera….
Apart from that, there are HEAPS of resources on the internet about photography, PLENTY. 
Basically, I’m learning myself … so I currently don’t have the terminology to tell you much about lenses.
All I can say is that … by numbers … I’m assuming you mean the numbers on the lenses, such as “18-55mm” …. which is the focal length. You will get more of the scene in your picture at 18mm than at 55mm … play around with it, and you’ll get the picture [excuse the pun].
Part – 5 | DSLR Lenses